[DanEC]

You can set the idle mixture with a vacuum gage or a tach. I've gotten to where I prefer a tach in recent years but I still use a vacuum gage sometimes. You should tune each side to achieve the highest vacuum or idle rpm separately - going back and forth a couple of times. On most motors the adjustments will end up pretty close to each other - but yeah, there may be a little difference in where the screws end up from side to side.